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removing implied casts in array index expressions

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This commit is contained in:
caheckman 2019-05-09 11:32:26 -04:00
parent f57af0b730
commit 706960a139
2 changed files with 39 additions and 5 deletions
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41
Ghidra/Features/Decompiler/src/decompile/cpp/printc.cc
View File

@ -577,8 +577,12 @@ void PrintC::opReturn(const PcodeOp *op)
void PrintC::opIntZext(const PcodeOp *op)
{
if (castStrategy->isZextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType()))
opTypeCast(op);
if (castStrategy->isZextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType())) {
if (isExtensionCastImplied(op))
pushVnImplied(op->getIn(0),op,mods);
else
opTypeCast(op);
}
else
opFunc(op);
}
@ -586,8 +590,12 @@ void PrintC::opIntZext(const PcodeOp *op)
void PrintC::opIntSext(const PcodeOp *op)
{
if (castStrategy->isSextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType()))
opTypeCast(op);
if (castStrategy->isSextCast(op->getOut()->getHigh()->getType(),op->getIn(0)->getHigh()->getType())) {
if (isExtensionCastImplied(op))
pushVnImplied(op->getIn(0),op,mods);
else
opTypeCast(op);
}
else
opFunc(op);
}
@ -1247,6 +1255,31 @@ bool PrintC::printCharacterConstant(ostream &s,const Address &addr,int4 charsize
return res;
}
/// \brief Is the given ZEXT/SEXT cast implied by the expression its in
///
/// We know that the given ZEXT or SEXT op can be viewed as a natural \e cast operation.
/// Sometimes such a cast is implied by the expression its in, and the cast itself
/// doesn't need to be printed.
/// \param op is the given ZEXT or SEXT PcodeOp
/// \return \b true if the op as a cast does not need to be printed
bool PrintC::isExtensionCastImplied(const PcodeOp *op) const
{
const Varnode *outVn = op->getOut();
if (outVn->isExplicit()) {
}
else {
PcodeOp *expOp = outVn->loneDescend();
if (expOp != (PcodeOp *)0) {
OpCode opc = expOp->code();
if (opc == CPUI_PTRADD)
return true;
}
}
return false;
}
/// \brief Push a single character constant to the RPN stack
///
/// For C, a character constant is usually emitted as the character in single quotes.

3
Ghidra/Features/Decompiler/src/decompile/cpp/printc.hh
View File

@ -153,9 +153,10 @@ protected:
void emitCommentGroup(const PcodeOp *inst); ///< Emit comments associated with a given statement
void emitCommentFuncHeader(const Funcdata *fd); ///< Emit comments in the given function's header
void opFunc(const PcodeOp *op); ///< Push a \e functional expression based on the given p-code op to the RPN stack
void opTypeCast(const PcodeOp *op); ///< Pus the given p-code op using type-cast syntax to the RPN stack
void opTypeCast(const PcodeOp *op); ///< Push the given p-code op using type-cast syntax to the RPN stack
static bool hasCharTerminator(uint1 *buffer,int4 size,int4 charsize);
bool printCharacterConstant(ostream &s,const Address &addr,int4 charsize) const;
bool isExtensionCastImplied(const PcodeOp *op) const;
virtual void pushConstant(uintb val,const Datatype *ct,
const Varnode *vn,const PcodeOp *op);
virtual bool pushEquate(uintb val,int4 sz,const EquateSymbol *sym,